Find the sum `cot^(-1) 2 + cot^(-1) 8 + cot^(-1) 18 + ...oo`

Find- cot^(-1)1+cot^(-1)2+cot^(-1)3

If cot^(-1) ( alpha) = cot^(-1)(2) + cot^(-1)(8) + cot^(-1)(18) + cot ^(-1)(32) + "…………" upto 100 terms , then alpha is :

Find the sum of the series cot^(-1) 7+cot^(-1)13+cot^(-1)21+cot^(-1)31+... to n terms

Prove that 2cot^(-1)5+ cot^(-1)7 + 2cot^(-1)8 =pi/4

Find the domain of cot x+cot^(-1)x